The specification describes transition metal complexes. The metal of the complex is coordinated to an ancillary ligand that is bulky and stably bonded to the transition metal. The ligand is derived from a neutral ligand precursor. The ligand may be coordinated to the transition metal by covalent bond and/or electron donation coordination.
Suitable transition metal complexes such as metallocenes and pyridine amine complexes may be used in olefin oligomerization, involving the linking of a limited number of monomer units or in olefin polymerization wherein numerous monomer units are joined to form a polymer chain.
The transition metal complexes are generally activated to perform their polymerization or oligomerization function. Activation involves, according to current theory, transformation of the neutral complex into a cation after interaction with a so-called activator.
The invention is especially concerned with pyridyl amine transition metal complexes of the type described in WO 02/038628 A2. An example of the preparation of ligand precursors is set out on pages 75-79 of WO 02/038628. A dihalo-pyridine is reacted with n-butyllithium and then dimethylformamide to produce a 2-bromo-6-formyl pyridine. This product is reacted with naphthylboronic acid to form 2-formyl-6-naphthylpyridine. This in turn is reacted with 2,6-diisopropylaniline to form 6-naphthyl-2-(2,6-diisopropylphenylimine)pyridine. This is reacted to give the amine with a free hydrogen atom on the bridging nitrogen atom. Page 78 discloses different ligands options.
There still is need for adding synthetic routes to broaden the performance envelopes catalysts of transition metal complexes having pyridyl-based ligands capable of reacting with alkenes.